1. Field of the Invention
This invention relates to oriented particles in hard surfaces and more particularly to an article providing a hard surface of oriented crystals for use in abrading, cutting, grinding and the like, and for use in other applications where hard surfaces are used, and to a method for making the article.
2. Discussion of the Prior Art
Hard or wear-resistant surfaces for use as abrasives in material-removal as in abrading, grinding and cutting, and for use in other application, have typically been made of particles or grits of a hard material embedded in a resinous or metallic matrix attached to a wheel, belt or other material-working tool. The grits used in the prior art have been of various hard materials, including diamond and cubic boron nitride (CBN).
The grits or particles of the prior art have been incorporated in the matrix in either a random manner or an oriented manner. The prior art orientation has been to disperse the grits uniformly, as in the U.S. Pat. No. 4,925,457 to deKok et al., dated May 15, 1990; to arrange planar faces of the grits so they seat flat against a workpiece, as in the U.S. Pat. No. 3,230,672 to Anthon, dated Jan. 25, 1966; or to orient the grit particles by electrostatic or electromagnetic means to provide better cutting surfaces, as in U.S. Pat. No. 4,240,807 to Kronzer, dated Dec. 23, 1990 and U.S. Pat. No. 5,203,881 to Wiand, dated Apr. 20, 1993.
Although these orientations may provide useful abrasive articles, these and like prior art abrasive or wear-resistant articles have failed to take advantage of the maximum hardness available in the abrasive materials used, such as diamond and CBN. The concept of orienting particles in a matrix so as to transfer to the abrasive surface as a whole the hardness qualities of the individual particles per se has not been recognized. Thus, it has not been known how to control the hardness of the surface either to insure that the resulting surface would have the maximum hardness possible or to provide a predetermined degree of hardness.
It has long been known that diamond crystals have a very high degree of abrasion resistance and that this resistance varies with the crystallographic direction of abrasion by a factor of as much as about one hundred times. This most resistant direction is along the diagonal of a cubic face in the plane of the face. (See Denning, R. M. "Directional Grinding Hardness in Diamond," American Mineralogist, (1953) 38, 108-117.)
Until the present invention, however, it has not been recognized how to take advantage of such crystallographic directions of hardness of diamond, CBN, and perhaps other materials, when these materials are employed to make an article having wear-resistant or abrasive qualities. Thus, the prior art devices have not optimized the hardness characteristics of a hard surface including particles of a hard material, such as diamond and CBN.